Final review stat

Thirty randomly selected students took the calculus final. If the sample mean was 92 and the standard deviation was 9.4, construct a 99 percent confidence interval for the mean score of all students from which the sample was gathered.

• 89.08 < μ < 94.92

• 87.27 < μ < 96.73

• 87.29 < μ < 96.71

• 87.77 < μ < 96.23

What is the critical value (z-score) for a 99% confidence interval? Round to 3 decimals.

• 2.326

• 1.96

• 1.645

• 2.576

The standard error of the proportion is calculated as:

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Alma is estimating the proportion of students in her school district who, in the past month, read at least 1 book. From a random sample of 50 students, she found that 32 students read at least 1 book last month. Assuming all conditions for inference are met, which of the following defines a 90 percent confidence interval for the proportion of all students in her district who read at least 1 book last month?

Identify the confidence interval used in the figure below if each shaded area is equal to 0.05.

• 90%
• 95%
• 98%
• 99%

A sample of 400 racing cars showed that 80 cars cost over $700,000. What is the 99% confidence interval of the true proportion of cars costing over $700,000?

• 0.001 < p < 0.005
• 0.566 < p < 0.693
• 0.148 < p < 0.252
• 0.023 < p < 0.045

You are conducting a study to see if the accuracy rate for fingerprint identification is significantly less than 0.72. Thus you are performing a left-tailed test. Your sample data produce the test statistic z=-2.043. Find the p-value accurate to 4 decimal places.

If n=29, x¯(x-bar)=46, and s=4, find the margin of error at a 98% confidence level

Give your answer to two decimal places.

You are conducting a study to see if the probability of catching the flu this year is significantly different from 69%. With H₁ : p ≠ 69% you obtain a test statistic of z=-2.139. Find the p-value accurate to 4 decimal places.

The p-value for a hypothesis test turns out to be 0.07972. At a 3% level of significance, what is the proper decision?

• • Reject H_0

• Fail to reject H_0